A representative method of preparing an organopolysiloxane is a method of dehydrating and condensing an organosilane or organosiloxane containing a hydrolytic group such as an alkoxy group. For example, the patent document 1 disclosed a method of preparing an organopolysiloxane, which includes dehydrating a disiloxane, a dialkoxydiorganosilane and a trialkoxyorganosilane, followed by condensing the disiloxane, dialkoxydiorganosilane and trialkoxyorganosilane.
However, it is difficult to effectively prepare an organopolysiloxane having a desired structure using this method. For example, a polysiloxane having a sufficiently long linear structure including a difunctional siloxane unit may not be easily prepared using this method. Also, a polysiloxane having a structure in which silicon atoms of a difunctional siloxane unit are directly connected to silicon atoms of a trifunctional siloxane unit by means of oxygen atoms may not be easily realized using this method.
In this method, it is difficult to remove functional groups which take part in dehydration and condensation reactions, for example, a hydroxyl group or a hydrolytic functional group such as an alkoxy group, from the prepared organopolysiloxane. However, the residual functional groups may have an adverse effect on physical properties of the prepared organopolysiloxane.